The study was conducted by a group of Norwegian researchers who examined the health records of over 85,000 children born in the country between 1999 and 2009 to see if they had been diagnosed with some kind of autism disorder. The researchers also looked at questionnaires filled out by the mothers to determine how much folic acid they had consumed in the month before they became pregnant and in the first eight weeks of pregnancy.

Of the 85,176 children in the study, 32 percent (270) were diagnosed with ASD. Thirteen percent (114) had autistic disorder, 7 percent (56) had Asperger’s, and 12 percent (100) were diagnosed with “pervasive developmental disorder-not otherwise specified.”

However, according to the researchers, the study “does not establish a causal relation between folic acid use and autistic disorder but provides a rationale for replicating the analyses in other study samples and further investigating genetic factors and other biological mechanisms that may explain the inverse association.”

“The finding that periconceptional supplement use might reduce the risk of autism is encouraging; however, it is important to confirm this finding in other population-based birth cohorts,” said Dr. Robert Barry of the CDC’s Division of Birth Defects and Developmental Disorders.

In Norway, it is recommended that women take 400 micrograms of folic acid per day. In the US, however, women may consume more than this amount because the Food and Drug Administration (FDA) has required certain food products to be fortified with folic acid since 1998. As a result, a cup of Cheerios has more than the recommended serving with 493 micrograms of folic acid.